German Published Application Nos. 1,975,010; 2,022,064; 2,136,340; 2,152,141; 2,301,728; 2,304,060; 2,304,098, 2,309,463; 2,363,730; 2,431,718; 2,512,616; 2,527,793; 2,559,224; 2,559,225; 2,609,752; 2,646,057; 2,635,913; 2,658,073; 2,709,463; 2,709,476; 2,948,921; European Published Application Nos. 8,142; 19,315; 28,865 and 28,866; French Pat. No. 1,397,399; and U.S. Pat. No. 3,860,536 teach liquid laundry detergents with varying quantities of nonionic surfactants, frequently present in a mixture with soaps and anionic surfactants of the sulfonate or sulfate type. These products are essentially free of inorganic builders such as condensed alkali metal phosphates, silicates and carbonates. They frequently contain enzymes and suitable stabilizers therefor, as well as alkanolamines, especially triethanolamine, and small amounts of polyacids, such as citric acid and polyphosphonic acids. The nonionic surfactants are generally derived from alkylphenols or fatty alcohols or oxo-alcohols of different chain length and display different degrees of alkoxylation depending on their desired effect. Basically, however, the only alkoxylation products which have been disclosed are those whose polyglycol ether residue is made up of ethylene glycol residues, regardless of the degree of alkoxylation. In contrast to these, it is known that polypropylene glycol ether groups do not possess hydrophilic properties, and therefore propoxylated fatty alcohols or alkylphenols are considered unsuitable for use in concentrated aqueous liquid laundry detergents.
German Published Application No. 2,810,703 discloses nonionic surfactants obtained by simultaneous or alternating addition of ethylene oxide and propylene oxide to higher alcohols. In the glycol ether residues in that Application the ethylene and propylene glycol groups are present in random distribution or repeated alternation. Compared to related alkoxylates of the general formulas EQU R--O--X--Y and R--O--Y--X
(X=polyethylene glycol group, Y=polypropylene glycol group), these compounds have a lower melting point and should therefore be substantially more suitable for use in liquid laundry detergents and have a higher laundering power toward fatty and mineral soils than the compound types given by the above formulas.
In addition, German Published Application No. 2,724,349 describes spray dried laundry detergents produced using alkoxylates ates of the preceding formula R--O--Y--X. However, there is no teaching of the production of liquid laundry detergents in this publication. The same is true for U.S. Pat. No. 4,280,919 in which the use of such alkoxylation products as low foam, biodegradable surfactants in laundry detergents and cleaning agents is suggested. In addition, U.S. Pat. No. 2,174,761 dated 1939, in which alkoxylates of the type in question were first described, gives no disclosure of liquid laundry detergents which would fulfill the current requirements for stability and laundering properties, the latter having become greatly increased compared to those of the year of publication of this patent.
The liquid laundry detergents based on ethoxylated fatty alcohols described in the first paragraph above have sufficient laundering ability relative to mineral and fat-containing soils and--insofar as they also contain proteases and suitable stabilizing agents for the latter--toward protein-containing stains as well. On the other hand, the laundering ability may not be fully satisfactory in relation to bleachable soils, especially stubborn tea stains. Since oxidizing bleaches are unsuitable in view of their insufficient stability in aqueous preparations and especially their destructive effect toward enzymes, a need exists for a suitable composition which is more effective with respect to colored soils without a decrease in laundering power relative to the other impurities. These characteristics were not to be expected of the compounds of formula R--O--Y--X, since the cited German Published Application No. 2,810,703 teaches that such surfactants have a reduced laundering capacity and are not very suitable for liquid concentrates because of their high melting point.